Over 50% of patients with active MS have abnormal sympathetic nervous system function & increased expression of lymphocyte beta-adrenergic receptors. In animal models of MS, EAE, sympathetic damage increases lymphocyte beta- receptor density & amplifies disease. Isoproterenol, a beta-adrenergic agonist prevents EAE. We will test the safety of the beta-adrenergic agonist terbutaline in patients with MS & assess cardiac, neurologic, sympathetic nervous system & immune function during one month of treatment.